The 51-year-old has been in charge of the likes of Bologna, Lazio and Palermo and replaces the Dutchman who was sacked less than three months into his reign
Inter have turned to former Lazio head coach Stefano Pioli as the man to turn their stuttering start to the season around.
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The Nerazzurri sacked Frank de Boer last week following their 1-0 Serie A defeat to Sampdoria, the Dutchman having only overseen two wins from their previous eight matches in all competitions.
Marcelino and Pioli were heavily linked to take over as De Boer’s replacement, but it is the latter who has been tasked with reviving their fortunes.
Pioli, 51, has agreed a two-year contract at San Siro and will be presented to the media on Thursday before Inter for the first time in the Milan derby after the international break.
Inter become Pioli’s 11th club, with his previous tenure at Lazio having seen him guide the club to third place in his first season, but his second campaign was not as prosperous and he was sacked in April after a 4-1 defeat to city rivals Roma.
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Despite significant investment ahead of the 2016-17 season, Inter have struggled to live up to expectations with only five wins in 12 league matches. They currently sit 13 points behind Serie A leaders Juventus, and 12 ahead of bottom side Crotone, who they beat 3-0 on Sunday.
The latest was a 3-0 victory over Crotone under the guidance of interim boss Stefano Vecchi, but that only lifted Inter into ninth position.
Hopes of a strong European campaign are also hanging in the balance as they sit bottom of Europa League Group K after three defeats in four matches.